1. Field of the Invention
This invention relates to an air conditioning apparatus.
2. Description of the Related Art
Equipment for the thermal conditioning of air usually includes a mechanical refrigeration apparatus to transfer heat between a conditioned air stream and a thermal reservoir, for example, ambient air. The refrigeration apparatus will include two heat exchangers, one acting as an evaporator and the other as a condenser for refrigerant circulated in the refrigeration apparatus. By locating one heat exchanger in the conditioned air stream and incorporating a reverse cycle control in the refrigeration apparatus it is possible to provide heating or cooling to the conditioned air stream. For heating the heat exchanger acts as a condenser and for cooling it acts as an evaporator. Alternatively, the refrigeration apparatus may provide dehumidification by placing both heat exchangers in the conditioned air stream such that the conditioned air stream is cooled at the first heat exchanger (evaporator) and then heated at the second heat exchanger (condenser).
In order to make possible all three thermal air conditioning functions, that is heating, cooling and dehumidification it is necessary either to provide means for directing the conditioned air stream through the desired heat exchanger individually for heating or cooling and through both heat exchangers for dehumidification. Alternatively it is possible to provide a refrigeration apparatus having a reverse cycle together with a supplementary heating element for use during dehumidification. The first approach requires extensive air flow control equipment and makes the unit physically larger in size. The latter approach maintains a simple air handling system but it must include some means of re-heating the conditioned air stream when dehumidification is required, for example by way of a supplementary heating element. A further disadvantage of the latter approach is its energy inefficiency, wherein heat is rejected to the outside air stream while additional heat must be produced to reheat the conditioned air stream.
The present invention is directed towards providing an improved air conditioning apparatus which overcomes these problems.